The present invention relates to detecting rib metastasis in computed tomography (CT) volumes, and more particularly to a system and method for automatic detection of rib metastasis in CT volumes.
Computed tomography (CT) is a medical imaging method whereby digital geometry processing is used to generate a three-dimensional image of the internal features of a patient from a large series of two-dimensional X-ray images taken around a single axis of rotation. Such CT imaging results in CT volume data which is a virtual representation of internal anatomical features of a patient. The CT volume data consists of multiple slices, or two-dimensional images, that can be combined to generate a three dimensional image. CT imaging is particularly useful because it can show several types of tissue including lung, bone, soft tissue and blood vessels, with great clarity. Accordingly, such imaging of the body can be used to diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal disorders.
CT imaging is commonly used to diagnose rib metastasis. Metastasis is the spread of cancer from its primary site to other places in the body. Rib metastasis is caused by cancerous cells from a primary tumor relocating to the ribs. Approximately 170,000 new cases of bone metastasis are diagnosed annually in the United States. Over 500,000 Americans live with bone metastasis. Primary carcinomas that frequently metastasize to bone include those from breast, lung, prostate, kidney, thyroid, stomach, and intestinal cancer. Accordingly, the diagnosis of bone metastasis can play a key role in cancer staging. Ribs are important sites to detect metastasis because they are more accessible to biopsy than other sites in the body, such as the lungs.
In order to diagnose rib metastasis, a doctor typically searches for rib metastasis in chest CT images generated from a CT volume data. A typical CT volume data set can contain hundreds of slices. The doctor must typically look at hundreds of such slices and on each slice study each of the rib intersections to look for possible metastasis. This diagnosis process is tedious and prone to error since the ribs typically cross through the axial slices at oblique angles. Consequently, each axial slice must be systematically evaluated by a doctor both to detect subtle abnormalities representing metastasis, and to determine which specific ribs are involved when abnormalities are detected. Accordingly, a method for automatically detecting rib metastasis is desirable.